Optical Coherence Tomography Angiography in Mice: Quantitative Analysis After Experimental Models of Retinal Damage

Abstract

PURPOSE. We implemented optical coherence tomography angiography (OCT-A) in mice to: (1) develop quantitative parameters from OCT-A images, (2) measure the reproducibility of the parameters, and (3) determine the impact of experimental models of inner and outer retinal damage on OCT-A findings. METHODS. OCT-A images were acquired with a customized system (Spectralis Multiline OCT2). To assess reproducibility, imaging was performed five times over 1 month. Inner retinal damage was induced with optic nerve transection, crush, or intravitreal N-methyl-d-aspartic acid injection in transgenic mice with fluorescently labeled retinal ganglion cells (RGCs). Light-induced retinal damage was induced in albino mice. Mice were imaged at baseline and serially post injury. Perfusion density, vessel length, and branch points were computed from OCT-A images of the superficial, intermediate, and deep vascular plexuses. RESULTS. The range of relative differences measured between sessions across the vascular plexuses were: perfusion density (2.8%-7.0%), vessel length (1.9%-4.1%), and branch points (1.9%-5.0%). In mice with progressive RGC loss, imaged serially and culminating in around 70% loss in the fluorescence signal and 18% loss in inner retinal thickness, there were no measurable changes in any OCT-A parameter up to 4 months post injury that exceeded measurement variability. However, light-induced retinal damage elicited a progressive loss of the deep vascular plexus signal, starting as early as 3 days post injury. CONCLUSIONS. Vessel length and branch points were generally the most reproducible among the parameters. Injury causing RGC loss in mice did not elicit an early change in the OCT-A signal.

Neuroprotective Properties of Dimethyl Fumarate Measured by Optical Coherence Tomography in Non-inflammatory Animal Models

“…Numerous other studies in rodents investigating retinal degeneration after ONC also found a decrease of the RNFL and TRT, as well as a loss of retinal ganglion cells (26)(27)(28)(29). After a light-induced retinal damage, authors essentially found degeneration of the ORL and photoreceptors, in line with our results (30,31).…”

Comparative study of optical coherence tomography angiography algorithms for rodent retinal imaging

“…33,34 All the linear-scale images were denoised, binarized, and skeletonized prior to the quantitative analysis. 35 BVD is defined as the ratio of the total image area occupied by the vasculature to the total area in an OCTA image…”

Response of the Trilaminar Retinal Vessel Network to Intraocular Pressure Elevation in Rat Eyes

“…Similar to the approach of Smith et al, 15 , and total retinal thickness [TRT]) and three vascular plexi (SVC, ICP, and DCP) was conducted using the automated software in-built into the imaging platform (Heidelberg Engineering). Each volume was checked for segmentation errors.…”

“…The advent of optical coherence tomography angiography (OCTA) has facilitated clinical and laboratory studies of the normal trilaminar vasculature 2,13,14 and the impact of a range of retinal conditions on the vasculature. [15][16][17] A number of investigations have used OCTA to investigate how the retinal and optic nerve vasculature responds to acute IOP elevations. 18 Zhang et al 19 showed in human subjects, that IOP elevation of 10 to 15 mm Hg above baseline induced via a dark-room prone test did not affect OCTA vessel density.…”